JP5644786B2 - Control device for voltage converter - Google Patents

Description

  The present invention relates to a technical field of a control device for a voltage conversion device mounted on, for example, a vehicle.

  2. Description of the Related Art In recent years, as an environmentally-friendly vehicle, an electric vehicle that is mounted with a power storage device (for example, a secondary battery or a capacitor) and travels using a driving force generated from electric power stored in the power storage device has attracted attention. Examples of the electric vehicle include an electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

  In these electric vehicles, a motor generator for generating driving force for traveling by receiving electric power from the power storage device when starting or accelerating, and generating electric power by regenerative braking during braking to store electric energy in the power storage device May be provided. Thus, in order to control a motor generator according to a driving | running | working state, an inverter is mounted in an electric vehicle.

  In such a vehicle, a voltage conversion device (converter) may be provided between the power storage device and the inverter in order to stably supply power used by the inverter that varies depending on the vehicle state. With this converter, the inverter input voltage can be made higher than the output voltage of the power storage device to increase the output of the motor and reduce the motor current at the same output, thereby reducing the size and cost of the inverter and motor. Can be achieved.

  In order to further improve the fuel efficiency of the electric vehicle, it is important to improve the efficiency by reducing the loss of the converter. For this reason, for example, Patent Documents 1 to 3 propose techniques for switching driving the boost converter with only one arm. According to such a technique, it is said that the loss of the converter can be reduced as much as the current ripple can be reduced.

JP 2011-120329 A JP 2006-074932 A International Publication No. 2010-137127

  When performing single-arm drive, it is required to switch the arm to be driven as the current direction switches from positive (ie, power running) to negative (ie, regeneration) via 0. Further, in the vicinity of zero current where the reactor current is in the discontinuous mode, it is required to perform nonlinear control on the reactor current instead of normal control. As a result of the above, it is considered that it is important to perform control after accurately grasping the timing when the reactor current becomes zero at the time of one-arm drive.

However, for example, in a general current sensor, an electromagnetic steel plate (core) is magnetized during use, and thus there is a possibility that an offset occurs in the acquired current value. The offset can be corrected, for example, when no current is flowing, but correction when the current is flowing is difficult, and therefore it is difficult to always detect an accurate current value by the current sensor. Therefore, it cannot be said that it is easy to execute appropriate control at an appropriate timing when driving one arm. As described above, when the one arm driving described in Patent Documents 1 to 3 described above is performed. Since it is difficult to accurately detect a current value in the vicinity of zero current, there is a technical problem that appropriate control may not be performed when the arm is switched.

  The present invention has been made in view of the above-described problems, and provides a control device for a voltage conversion device capable of accurately detecting a current value of a current flowing through the voltage conversion device and executing appropriate drive control. The task is to do.

In order to solve the above-described problem, the voltage converter control device of the present invention selectively turns on the first switching element and the second switching element that are connected in series with each other, so that the first switching element is turned on. A control device for a voltage converter capable of realizing single-arm driving by only one of a first arm and a second arm including the second switching element, wherein the first switching element and the first switching element Switching control signal generating means for generating a switching control signal for switching on / off of each of the two switching elements, and the switching control when the one-arm driving by the first arm and the one-arm driving by the second arm are mutually switched. At the rising edge of the signal, the first switching element or the second switching element is Current detection means for detecting a current value of the drive current to be detected, current estimation means for estimating an average value of the drive current using the detected current value, and the drive current based on the estimated average value Current control means for controlling , wherein the current estimation means is such that an average value of the drive current is near zero when the detected current value is continuously within a predetermined range. And when the average value of the drive current is estimated to be a value near zero, the current control means performs the near-zero control corresponding to the near-zero value. To control .

  The voltage converter according to the present invention is a converter mounted on a vehicle, for example, and includes a first switching element and a second switching element connected in series with each other. As the first switching element and the second switching element, for example, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or a power bipolar transistor can be used.

  For example, a diode is connected in parallel to each of the first switching element and the second switching element to form a first arm and a second arm, respectively. In other words, the first switching element forms a first arm, and the switching operation of the first arm can be switched on and off. Similarly, the second switching element forms a second arm, and on / off of driving in the second arm can be switched by the switching operation.

  In addition, the voltage conversion device according to the present invention particularly controls the first switching element and the second switching element to be selectively turned on, whereby the first arm and the second arm including the first switching element are controlled. One-arm drive by only one of the second arms including the switching element can be realized.

  When the one-arm drive is performed, it is determined which of the first arm and the second arm the one-arm drive should be performed based on, for example, a voltage value or a current value to be output. More specifically, for example, when a motor generator connected to the voltage converter performs a regenerative operation, the one-arm drive by the first arm is selected, and when the power running operation is performed, the one-arm drive by the second arm is selected. The As described above, when one arm is driven, the one arm driving by the first arm and the one arm driving by the first arm are appropriately switched.

  A control device for a voltage conversion device according to the present invention is a device that controls the operation of the voltage conversion device described above. For example, one or a plurality of CPUs (Central Processing Units), MPUs (Micro Processing Units), various processors, Various controllers, or various types such as a single or a plurality of ECUs (Electronic Controlled Units), which may appropriately include various storage means such as ROM (Read Only Memory), RAM (Random Access Memory), buffer memory or flash memory. It can take the form of various computer systems such as processing units, various controllers or microcomputer devices.

  During the operation of the control device for the voltage converter according to the present invention, the switching control signal generating means generates a switching control signal for switching on / off of each of the first switching element and the second switching element. Specifically, for example, a duty command signal corresponding to the duty ratio of the first switching element and the second switching element and a carrier signal corresponding to the switching frequency of the first switching element and the second switching element are compared with each other. A switching control signal is generated. The generated switching control signal is supplied to the first switching element and the second switching element, whereby the driving of the first arm and the second arm of the voltage converter is controlled.

  Here, particularly in the present invention, when the one-arm driving by the first arm and the one-arm driving by the second arm are switched to each other, the driving current by the current detecting means (that is, the current flowing through the first switching element or the second switching element). ) Is detected. Here, “when switching the one-arm drive by the first arm and the one-arm drive by the second arm to each other” means the moment when the on / off of each of the first switching element and the second switching element is switched. It is not a thing, but it is a broad concept including a period during which it can be determined that there is a possibility that the arm being driven may be switched (for example, a period in which the current value of the drive current is close to zero, which is the arm switching threshold). is there.

  Further, the detection of the current value of the drive current by the above-described current detection means is performed at the rising timing of the switching control signal for the driving switching element of the first switching element and the second switching element. For this reason, the detected current value of the drive current is the extreme value of the current value that periodically rises and falls as the switching element is turned on and off (the minimum value when the current value is positive and the maximum value when the current value is negative). Become. Note that the “rise timing” here does not mean only the moment when the pulse of the switching control signal rises, but if it is a timing at which the above-mentioned extreme value can be detected, it is a timing slightly deviated from the rise of the pulse. It does not matter.

  When the current value of the drive current is detected by the current detection means, the average value of the drive current is estimated from the detected current value by the current estimation means. Here, the “average value” does not mean an average value over a relatively long period, but an instantaneous average value of current values that periodically rise and fall depending on on / off of the switching element (that is, periodically) It means a substantial value in a relatively short period of the current value that rises and falls. For this reason, it can be said that the arm switching during the one-arm driving is preferably performed not at the time when the current value of the driving current temporarily becomes zero but at the time when the average value of the driving current becomes zero.

  When the average value of the drive current is estimated by the current estimation means, the drive current is controlled by the current control means based on the estimated average value of the drive current. That is, the current control means grasps the average value of the drive current and changes the drive current to a value to be realized. The current control unit controls the drive current by controlling the switching control signal generation unit so as to change the pulse width of the switching control signal, for example.

  Here, during the one-arm drive, the drive current flows only to one of the first switching element and the second switching element. For this reason, when the current value is positive, no negative current flows until the arm is switched. Therefore, the lower limit of the current value in this case is zero. Conversely, when the current value is negative, no positive current flows until the arm is switched. Therefore, the upper limit of the current value in this case is zero.

  When the current value changes under the above-described restrictions, when the average value of the drive current is close to zero, the periodic rise and fall of the current value is temporarily disturbed. For this reason, in the state where the average value of the drive current is close to zero, the control of the drive current becomes nonlinear and relatively complicated.

  However, in the present invention, in particular, as described above, the extreme value of the current value that rises and falls periodically is detected by the current detection means. Therefore, for example, when the detected current value does not change, it can be suitably determined that the average value of the drive current is close to zero, and the drive current can be appropriately controlled according to the situation. It becomes.

  As described above, according to the control device of the voltage conversion device according to the present invention, it is possible to accurately detect the current value of the current flowing through the voltage conversion device and execute appropriate drive control.

  In one aspect of the control device for a voltage converter according to the present invention, the current estimation means has an average value of the drive current close to zero when the detected current value is continuously within a predetermined range. When it is estimated that the value is near zero, the current control means performs the near-zero control corresponding to the near-zero value when the average value of the drive current is estimated to be the near-zero value. Controls the switching control signal generating means.

  According to this aspect, when the current value detected by the current detection unit is continuously within the predetermined range, the current estimation unit estimates that the average value of the drive current is near zero. Is done. Here, the “predetermined range” is a threshold value for determining that the current values continuously detected are extremely close to the same or the same level, and the current value detection accuracy, etc. It is preset based on The “near zero value” here is a value corresponding to an average value of the drive current indicating that the waveform of the drive current is limited by reaching zero, and the detected current It can be estimated that the value is continuously within a predetermined range (that is, the detected current value has reached zero which is a limit value).

  When it is estimated that the average value of the drive current is a value near zero, the switching control signal generating means is controlled by the current control means so as to perform the near-zero control corresponding to the near-zero value. Here, “near zero control” is drive control different from normal required when the drive current approaches zero. For example, nonlinear control that gradually reduces the pulse width of the switching control signal. Control.

  According to this aspect, it can be estimated that the average value of the drive current is a value near zero under the condition that the current value detected by the current detection means is continuously within the predetermined range. Therefore, it is possible to control the voltage converter more suitably.

  In the aspect in which it is possible to estimate that the average value of the driving current is a value near zero, the zero current estimation is performed to estimate the current value when the detected current value is continuously within a predetermined range as zero. And zero timing estimation means for estimating a timing at which the average value of the drive current becomes zero based on a transition of the current value estimated to be zero and the average value of the drive current, and the current control means Controls the switching control signal generation means so that the average value of the drive current becomes zero at the zero timing.

  According to this aspect, when the current value of the drive current detected by the zero current estimation unit is continuously within the predetermined range, the current value continuously within the predetermined range is the upper limit value or the lower limit value. The value zero is estimated. Note that if there is a difference between two current values that are continuously in a predetermined range, one of them may be estimated to be zero. Or you may estimate that the average value of two electric current values is zero.

  When the current value of zero is estimated, the timing at which the average value of the drive current becomes zero is estimated by the zero timing estimation means. The zero timing estimation means estimates the zero timing based on the transition of the current value estimated to be zero and the average value of the drive current. More specifically, the zero timing estimation means estimates, for example, a point where a line obtained by extending a line indicating a transition of the average value of the drive current and a current value estimated to be zero crosses as zero timing.

  When the zero timing is estimated, the switching control signal generating means is controlled by the current control means so that the average value of the drive current becomes zero at the zero timing. That is, the estimated zero timing is used in a feed-forward manner for control of the drive current by the current control means. This ensures that the drive current is zero at zero timing. Therefore, it is possible to suitably execute the control when the drive current becomes a value near zero.

  In the aspect of estimating the zero timing described above, the current control means generates the switching control signal generation means so that the one arm driving by the first arm and the one arm driving by the second arm are switched to each other at the zero timing. May be controlled.

  In this case, since the zero timing at which the average value of the drive current becomes zero is accurately estimated by the zero timing estimation means, the arm switching control by the current control means can be suitably executed. Therefore, it is possible to effectively prevent a problem that occurs due to the arm switching timing deviating from the zero timing.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

It is the schematic which shows the whole structure of the vehicle by which the control apparatus of the voltage converter which concerns on embodiment is mounted. It is a chart figure showing change of current value at the time of both arm drive. It is a conceptual diagram which shows the flow of the electric current at the time of a lower arm drive. It is a conceptual diagram which shows the flow of the electric current at the time of an upper arm drive. It is a chart figure showing change of current value at the time of one arm drive. It is a flowchart which shows operation | movement of the control apparatus of the voltage converter which concerns on embodiment. It is the chart figure (the 1) which shows the control method of a voltage converter later on. It is the chart figure (the 2) which shows the control method of a voltage converter later on. It is the chart figure (the 3) which shows the control method of a voltage converter later on. It is the chart figure (the 4) which shows the control method of a voltage converter later on.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an overall configuration of a vehicle in which a control device for a voltage converter according to the present embodiment is mounted will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of a vehicle in which the control device for a voltage conversion device according to this embodiment is mounted.

  In FIG. 1, a vehicle 100 on which a control device for a voltage converter according to this embodiment is mounted is configured as a hybrid vehicle using an engine 40 and motor generators MG1 and MG2 as power sources. However, the configuration of the vehicle 100 is not limited to this, and the vehicle 100 can be applied to a vehicle (for example, an electric vehicle or a fuel cell vehicle) that can be driven by electric power from the power storage device. Moreover, although this embodiment demonstrates the structure mounted in the vehicle 100 by the control apparatus of a voltage converter, it is applicable if it is an apparatus driven by an AC motor other than a vehicle.

  The vehicle 100 includes a DC voltage generator 20, a load device 45, a smoothing capacitor C2, and an ECU 30.

  DC voltage generation unit 20 includes a power storage device 28, system relays SR1 and SR2, a smoothing capacitor C1, and a converter 12.

  The power storage device 28 includes a secondary battery such as nickel hydride or lithium ion, and a power storage device such as an electric double layer capacitor. Further, the DC voltage VB output from the power storage device 28 and the input / output DC current IB are detected by the voltage sensor 10 and the current sensor 11, respectively. Then, the voltage sensor 10 and the current sensor 11 output detected values of the detected DC voltage VB and DC current IB to the ECU 30.

  System relay SR1 is connected between the positive terminal of power storage device 28 and power line PL1, and system relay SR2 is connected between the negative terminal of power storage device 28 and ground line NL. System relays SR <b> 1 and SR <b> 2 are controlled by a signal SE from ECU 30, and switch between supply and interruption of power from power storage device 28 to converter 12.

  Converter 12 is an example of the “voltage converter” of the present invention, and includes a reactor L1, switching elements Q1 and Q2, and diodes D1 and D2. The switching elements Q1 and Q2 are examples of the “first switching element” and the “second switching element” of the present invention, and are connected in series between the power line PL2 and the ground line NL. Switching elements Q1 and Q2 are controlled by a switching control signal PWC from ECU 30.

  As the switching elements Q1 and Q2, for example, an IGBT, a power MOS transistor, a power bipolar transistor, or the like can be used. Anti-parallel diodes D1 and D2 are arranged for switching elements Q1 and Q2. Reactor L1 is provided between a connection node of switching elements Q1 and Q2 and power line PL1. Smoothing capacitor C2 is connected between power line PL2 and ground line NL.

  The current sensor 18 is an example of the “current detection means” in the present invention, detects the reactor current flowing through the reactor L1, and outputs the detected value IL to the ECU 30.

  Load device 45 includes an inverter 23, motor generators MG <b> 1 and MG <b> 2, an engine 40, a power split mechanism 41, and drive wheels 42. Inverter 23 includes an inverter 14 for driving motor generator MG1 and an inverter 22 for driving motor generator MG2. As shown in FIG. 1, it is not essential to provide two sets of inverters and motor generators. For example, only one set of inverter 14 and motor generator MG1 or inverter 22 and motor generator MG2 may be provided.

  Motor generators MG1 and MG2 receive AC power supplied from inverter 23 and generate rotational driving force for vehicle propulsion. Motor generators MG1 and MG2 receive rotational force from the outside, generate AC power according to a regenerative torque command from ECU 30, and generate regenerative braking force in vehicle 100.

  Motor generators MG1 and MG2 are also coupled to engine 40 via power split mechanism 41. Then, the driving force generated by engine 40 and the driving force generated by motor generators MG1, MG2 are controlled to have an optimal ratio. Alternatively, either one of motor generators MG1 and MG2 may function exclusively as an electric motor, and the other motor generator may function exclusively as a generator. In the present embodiment, it is assumed that motor generator MG1 functions as a generator driven by engine 40, and motor generator MG2 functions as an electric motor that drives drive wheels 42.

  For the power split mechanism 41, for example, a planetary gear mechanism (planetary gear) is used in order to distribute the power of the engine 40 to both the drive wheels 42 and the motor generator MG1.

  Inverter 14 receives the boosted voltage from converter 12, and drives motor generator MG1 to start engine 40, for example. Inverter 14 also outputs regenerative power generated by motor generator MG <b> 1 by mechanical power transmitted from engine 40 to converter 12. At this time, converter 12 is controlled by ECU 30 to operate as a step-down circuit.

  Inverter 14 is provided in parallel between power line PL2 and ground line NL, and includes U-phase upper and lower arms 15, V-phase upper and lower arms 16, and W-phase upper and lower arms 17. Each phase upper and lower arm is composed of a switching element connected in series between power line PL2 and ground line NL. For example, the U-phase upper and lower arms 15 are composed of switching elements Q3 and Q4, the V-phase upper and lower arms 16 are composed of switching elements Q5 and Q6, and the W-phase upper and lower arms 17 are composed of switching elements Q7 and Q8. Antiparallel diodes D3 to D8 are connected to switching elements Q3 to Q8, respectively. Switching elements Q3 to Q8 are controlled by a switching control signal PWI from ECU 30.

  For example, motor generator MG1 is a three-phase permanent magnet type synchronous motor, and one end of three coils of U, V, and W phases is commonly connected to a neutral point. Further, the other end of each phase coil is connected to a connection node of switching elements of upper and lower arms 15 to 17 for each phase.

  Inverter 22 is connected to converter 12 in parallel with inverter 14.

  Inverter 22 converts the DC voltage output from converter 12 into three-phase AC and outputs the same to motor generator MG2 that drives drive wheels. Inverter 22 also outputs regenerative power generated by motor generator MG2 to converter 12 along with regenerative braking. At this time, converter 12 is controlled by ECU 30 to operate as a step-down circuit. Although the internal configuration of the inverter 22 is not shown, it is the same as that of the inverter 14 and will not be described in detail.

  Converter 12 is basically controlled such that switching elements Q1 and Q2 are turned on and off in a complementary manner in each switching period. During boosting operation, converter 12 boosts DC voltage VB supplied from power storage device 28 to DC voltage VM (this DC voltage corresponding to the input voltage to inverter 14 is also referred to as “system voltage” hereinafter). This boosting operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q2 to the power line PL2 via the switching element Q1 and the antiparallel diode D1.

  Further, converter 12 steps down DC voltage VM to DC voltage VB during the step-down operation. This step-down operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q1 to the ground line NL via the switching element Q2 and the antiparallel diode D2.

  The voltage conversion ratio (ratio between VM and VB) in these step-up and step-down operations is controlled by the on-period ratio (duty ratio) of the switching elements Q1 and Q2 in the switching period. Note that if the switching elements Q1 and Q2 are fixed to ON and OFF, respectively, VM = VB (voltage conversion ratio = 1.0) can be obtained.

  Smoothing capacitor C <b> 2 smoothes the DC voltage from converter 12 and supplies the smoothed DC voltage to inverter 23. The voltage sensor 13 detects the voltage across the smoothing capacitor C2, that is, the system voltage VM, and outputs the detected value to the ECU 30.

  When the torque command value of motor generator MG1 is positive (TR1> 0), inverter 14 responds to switching control signal PWI1 from ECU 30 when a DC voltage is supplied from smoothing capacitor C2, and switching elements Q3-Q8 The motor generator MG1 is driven so as to convert a DC voltage into an AC voltage and output a positive torque by the switching operation. Further, when the torque command value of motor generator MG1 is zero (TR1 = 0), inverter 14 converts the DC voltage into the AC voltage and the torque becomes zero by the switching operation in response to switching control signal PWI1. In this manner, motor generator MG1 is driven. Thus, motor generator MG1 is driven to generate zero or positive torque designated by torque command value TR1.

  Furthermore, during regenerative braking of vehicle 100, torque command value TR1 of motor generator MG1 is set negative (TR1 <0). In this case, inverter 14 converts the AC voltage generated by motor generator MG1 into a DC voltage by a switching operation in response to switching control signal PWI1, and converts the converted DC voltage (system voltage) to smoothing capacitor C2. To the converter 12. The regenerative braking here refers to braking with regenerative power generation when the driver operating the electric vehicle performs a footbrake operation, or regenerative braking by turning off the accelerator pedal while driving, although the footbrake is not operated. This includes decelerating (or stopping acceleration) the vehicle while generating electricity.

  Similarly, inverter 22 receives switching control signal PWI2 from ECU 30 corresponding to the torque command value of motor generator MG2, receives a switching control signal PWI2, and converts the DC voltage into an AC voltage to a predetermined torque by a switching operation. The motor generator MG2 is driven so that

  Current sensors 24 and 25 detect motor currents MCRT1 and MCRT2 flowing through motor generators MG1 and MG2, and output the detected motor currents to ECU 30. Since the sum of the instantaneous values of the currents of the U-phase, V-phase, and W-phase is zero, the current sensors 24 and 25 are arranged to detect the motor current for two phases as shown in FIG. All you need is enough.

  Rotation angle sensors (resolvers) 26 and 27 detect rotation angles θ1 and θ2 of motor generators MG1 and MG2, and send the detected rotation angles θ1 and θ2 to ECU 30. ECU 30 can calculate rotational speeds MRN1, MRN2 and angular speeds ω1, ω2 (rad / s) of motor generators MG1, MG2 based on rotational angles θ1, θ2. Note that the rotation angle sensors 26 and 27 may not be arranged by directly calculating the rotation angles θ1 and θ2 from the motor voltage and current in the ECU 30.

  Although not shown, ECU 30 includes a CPU (Central Processing Unit), a storage device, and an input / output buffer, and controls each device of vehicle 100. The ECU 30 is an example of the “voltage converter control device” according to the present invention. Specifically, the “switching control signal generation means”, “current estimation means”, “current control means”, “zero current estimation means”, and It has a function as “zero timing estimation means”. Note that the control performed by the ECU 20 is not limited to processing by software, and can be constructed and processed by dedicated hardware (electronic circuit).

  As representative functions, the ECU 30 includes the input torque command values TR1 and TR2, the DC voltage VB detected by the voltage sensor 10, the DC current IB detected by the current sensor 11, and the system voltage detected by the voltage sensor 13. Based on the motor currents MCRT1 and MCRT2 from the VM and current sensors 24 and 25, the rotation angles θ1 and θ2 from the rotation angle sensors 26 and 27, etc., the motor generators MG1 and MG2 generate torques according to the torque command values TR1 and TR2. The operations of the converter 12 and the inverter 23 are controlled so as to output. That is, switching control signals PWC, PWI1, and PWI2 for controlling converter 12 and inverter 23 as described above are generated and output to converter 12 and inverter 23, respectively.

  During the boosting operation of converter 12, ECU 30 feedback-controls system voltage VM and generates switching control signal PWC so that system voltage VM matches the voltage command value.

  Further, when vehicle 100 enters the regenerative braking mode, ECU 30 generates switching control signals PWI1 and PWI2 so as to convert the AC voltage generated by motor generators MG1 and MG2 into a DC voltage, and outputs it to inverter 23. Thus, inverter 23 converts the AC voltage generated by motor generators MG1 and MG2 into a DC voltage and supplies it to converter 12.

  Further, when vehicle 100 enters the regenerative braking mode, ECU 30 generates a switching control signal PWC so as to step down the DC voltage supplied from inverter 23 and outputs it to converter 12. Thus, the AC voltage generated by motor generators MG1 and MG2 is converted into a DC voltage, and is further stepped down and supplied to power storage device 28.

  Next, current fluctuations during the operation of converter 12 will be described with reference to FIGS. FIG. 2 is a chart showing the fluctuation of the current value when both arms are driven. FIG. 3 is a conceptual diagram showing the flow of current when driving the lower arm, and FIG. 4 is a conceptual diagram showing the flow of current when driving the upper arm. FIG. 5 is a chart showing the fluctuation of the current value when driving one arm.

  In FIG. 2, when converter 12 performs both-arm driving (that is, driving to turn on both switching elements Q1 and Q2), PWI1 and switching element Q2 which are switching control signals for switching on / off of switching element Q1. The value of the reactor current IL is controlled by supplying PWI2, which is a switching control signal for switching on and off, to the switching elements Q1 and Q2, respectively.

  When both arms are driven, a positive current and a negative current can be caused to flow by each of the switching elements Q1 and Q2. Therefore, even in current control over 0 as shown in the figure, the same control as usual is performed. Is possible.

  3 and 4, the converter 12 according to the present embodiment can realize one-arm drive in which only one of the switching elements Q1 and Q2 is turned on in addition to the above-described both-arm drive. ing. Specifically, during power running, lower arm drive is performed to turn on only switching element Q2. In this case, as shown in FIG. 3, the current flowing to the switching element Q1 side flows through the diode D1, and the current flowing to the switching element Q2 side flows through the switching element Q2. On the other hand, at the time of regeneration, lower arm driving is performed to turn on only switching element Q2. In this case, as shown in FIG. 3, the current flowing to the switching element Q1 side flows through the switching element Q1, and the current flowing to the switching element Q2 side flows through the diode D2.

  According to the one-arm drive, since only one of the switching elements Q1 and Q2 is turned on, a dead time set to prevent the switching elements Q1 and Q2 from being short-circuited becomes unnecessary. Therefore, for example, even when a higher frequency is required with the downsizing of the device, it is possible to prevent the boosting performance of the converter 12 from being deteriorated.

  In FIG. 5, at the time of power running in which the lower arm drive is performed (that is, when the reactor current IL is positive), PWI1 which is a switching control signal for switching on / off of the switching element Q1 is not supplied, and the switching element Q2 is turned on / off. Only PWI2, which is a switching control signal to be switched, is supplied. Further, at the time of regeneration when the upper arm drive is performed (that is, when the reactor current IL is negative), only PWI1 which is a switching control signal for switching on / off of the switching element Q1 is supplied, and switching for switching on / off of the switching element Q2 is performed. The control signal PWI2 is not supplied.

  In particular, since a negative current cannot flow when the lower arm is driven, when the lower limit of the reactor current IL is zero, the duty ratio of the switching control signal PWI2 is changed to be nonlinear. Control is required. Similarly, since a positive current cannot flow when the upper arm is driven, when the upper limit of the reactor current IL is zero, the duty ratio of the switching control signal PWI1 is changed to perform nonlinear control. Is required to do. That is, at the time of one-arm drive, when the reactor current IL approaches zero, relatively complicated control different from normal is required.

  The control device of the voltage conversion device according to the present embodiment aims to accurately determine that the reactor current IL has approached zero in order to suitably execute the above-described specific control during the one-arm drive.

  Next, the operation of the control device for the voltage converter according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing the operation of the control device of the voltage converter according to this embodiment. FIG. 7 to FIG. 10 are charts showing the control method of the voltage converter in order. In the following, the operation when the lower arm drive is switched to the upper arm drive will be described.

  6 and 7, when the control device of the voltage converter according to the present embodiment operates, first, the reactor current IL is detected by the current sensor 18 at the rising timing of the switching control signal PWI (step S101). Therefore, when vehicle 100 is in the power running state and the lower arm drive is performed, reactor current IL is detected at the rising timing of PWI2, which is a switching control signal corresponding to switching element Q2. If the reactor current IL is detected at such timing, it is possible to detect the minimum value of the reactor current IL that rises and falls according to the on / off of the switching element Q2, as can be seen from FIG.

  When reactor current IL is detected, ECU 30 estimates an average value of reactor current IL (step S102). The average value of the reactor current IL can be estimated using the detected value of the reactor current IL, for example. Alternatively, it can be estimated using the reactor current IL detected at a timing other than the rising timing of the switching control signal PWI2 (for example, the rising timing of the switching control signal PWI2 or the peak and valley timing of the carrier signal).

  6 and 8, the ECU 30 determines whether or not the reactor current IL detected by the current sensor 18 is continuously within a predetermined range (in other words, a state close to the same value). (Step S103). Here, if the reactor current IL, which should normally continue to fall, is continuously within a predetermined range (step S103: YES), it is considered that the lower limit of the reactor current IL has reached zero and is in a restricted state. be able to.

  In this case, the ECU 30 determines that the average value of the reactor current has become a value near zero, and the control of the converter 12 is switched from normal control to near-zero control corresponding to the value near zero (step S104). . Specifically, linear control in which the duty ratio of the switching control signal PWI2 does not change is switched to nonlinear control in which the duty ratio of the switching control signal PWI2 changes as shown in FIG.

  6 and 9, when near zero control is started, the ECU 30 estimates that the current value continuously within the predetermined range is the current zero point (step S105). In addition, it is estimated that the timing at which the line extending the transition of the average value of the reactor current IL and the current zero point cross is the zero timing at which the average value of the reactor current IL becomes zero (step S106).

  When the zero timing is estimated, near-zero control is performed by the ECU 30 so that the average value of the reactor current IL becomes zero at the zero timing. Specifically, the duty ratio of the switching control signal PWI2 is non-linearly controlled based on the zero timing. In this way, the estimated zero timing is used in a feed-forward manner for the control of the reactor current IL.

  6 and 10, the average value of the reactor current IL is gradually reduced by near zero control, and when the zero timing is reached (step S108: YES), the ECU 30 performs arm switching control (step S109). That is, the lower arm drive is switched to the upper arm drive. Specifically, the ECU 30 switches the arm by outputting a switching control signal PWI1 corresponding to the switching element Q1 instead of the switching control signal PWI2 corresponding to the switching element Q2.

  Here, particularly in the present embodiment, the timing at which the average value of the reactor current IL becomes zero is accurately estimated by the above-described estimation of the zero timing. Therefore, the arm can be switched at an extremely appropriate timing (that is, the average value of the reactor current IL is very close to zero). As a result, it is possible to effectively prevent problems that occur due to the shift of the arm switching timing.

  Although detailed description is omitted, after the arm is switched, near zero control during regeneration is performed instead of near zero control during power running. As a result, the drive current can be appropriately controlled even in the upper arm drive in which a positive current cannot be used.

  Incidentally, at the time of regeneration, the detection of the reactor current IL is performed at the rising timing of the switching control signal PWI1. Thereby, it is possible to determine whether or not the reactor current reaches zero and is limited in the same manner as in the power running described above. When the average value of the reactor current IL is reduced and does not reach zero (for example, when the detected reactor current IL is not continuously within a predetermined range), the converter 12 is controlled in a non-linear near zero control. To linear normal control.

  As described above, according to the control device of the voltage conversion device according to the present embodiment, it is possible to accurately detect the current value of the current flowing through the converter 12 and execute appropriate drive control. In the embodiment described above, the case where the lower arm drive is switched to the upper arm drive (that is, the case where the lower arm drive is switched from power running to regeneration) is described as an example. However, the upper arm drive is switched to the lower arm drive. The same control can be applied even in the case of switching from regeneration to power running.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. These control devices are also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 12 ... Converter, 18 ... Current sensor, 20 ... DC voltage generation part, 22, 23 ... Inverter, 28 ... Power storage device, 30 ... ECU, 40 ... Engine, 41 ... Power split mechanism, 42 ... Drive wheel, 45 ... Load device 100, vehicle, C2, smoothing capacitor, D1, D2 ... diode, IL ... reactor current, L1, reactor, MG1, MG2 ... motor generator, PWI1, PWI2 ... switching control signal, Q1, Q2 ... switching element, SR1, SR2 ... system relay.

Claims (3)

A first arm that includes the first switching element and a second arm that includes the second switching element are selectively turned on by alternately switching on the first switching element and the second switching element that are connected in series with each other. A control device for a voltage conversion device capable of realizing one-arm drive by only one of the arms,
Switching control signal generating means for generating a switching control signal for switching on and off each of the first switching element and the second switching element;
When switching between the one-arm drive by the first arm and the one-arm drive by the second arm, the current of the drive current flowing through the first switching element or the second switching element at the rising timing of the switching control signal Current detection means for detecting a value;
Current estimation means for estimating an average value of the drive current using the detected current value;
Current control means for controlling the drive current based on the estimated average value ,
The current estimating means estimates that the average value of the drive current is a value near zero near zero when the detected current value is continuously within a predetermined range;
The current control means controls the switching control signal generation means so as to perform near zero control corresponding to the near zero value when the average value of the drive current is estimated to be near zero value. A control device for a voltage conversion device. Zero current estimation means for estimating the current value when the detected current value is continuously within a predetermined range as zero;
Zero timing estimation means for estimating a timing at which the average value of the drive current becomes zero based on a transition of the current value estimated to be zero and the average value of the drive current;
2. The control device for a voltage converter according to claim 1 , wherein the current control unit controls the switching control signal generation unit so that an average value of the drive current becomes zero at the zero timing. 3. The current control means controls the switching control signal generation means so that the one-arm driving by the first arm and the one-arm driving by the second arm are switched to each other at the zero timing. 3. A control device for a voltage converter according to 2 .

Images